A detergent, soap, cleaner, wax, or any chemical could irritate your skin. Health care workers, florists, hairdressers, machinists, and cleaners get it more often. You might have an allergic reaction within a few hours, or it might happen over a longer period of time, as a chemical wears down the top, oily, protective layer of skin. Tell your doctor about your symptoms. Treatment depends on the cause.